Diagnosis, treatment, and management of diabetes and certain metabolic disorders require monitoring of glucose concentration in the blood. Despite many advances in the minimally invasive blood glucose monitoring, the currently used methods are expensive, cumbersome, time consuming, and do not provide accurate, real-time blood glucose concentration information. Thus, a need exists for a better long-term, minimally invasive glucose-monitoring system. Doing so non-invasively with minimal user maintenance is essential, and sensor longevity of days to months is crucial in actual user environments.
Such real-time, continuous measurement of glucose concentration in the blood can be achieved by the use of sensors inserted or implanted into the tissue and measuring the signal generated by the sensor by a device located outside the body. Luminescence provides a useful tool for the design of such sensors. The sensors, which are monitored optically through the skin, require a highly stable dye with excitation and emission spectra in the near-infrared (NIR) optical window of the skin. These dye properties are crucial for the successful design of a luminescent sensor that can be implanted deep into tissue. Monitoring non-invasively through the skin requires the use of dyes with excitation and emission wavelengths in the optical window of the skin (approximately 550 to 1100 nm) to minimize light scattering and absorbance, and to achieve a high signal-to-noise ratio. Presently used dyes require excitation with light which is largely absorbed by the skin and the underlying tissue. Additionally, the currently available sensors are made of rigid materials that vastly differ from the mechanical properties of tissue in which they are implanted, are bulky and inconvenient, and induce a series of biological events upon implantation that ultimately culminate in the formation of a fibrous capsule that walls it off from the body.
A need exists for glucose-sensing compositions that are Near IR-detectable, particularly in vivo, and are suitable for long-term, minimally invasive implantation into tissues.